Synthetic resins having various properties have been obtained in recent years as a result of advance of synthetic resin researches. Adding novel performance to existing resins without impairing the resin's own performance has been frequently attempted in such studies.
While acrylic resins and styrene resins as representative synthetic polymer materials have excellent features such as relatively cheap cost, good transparency, relatively easy preparation of polymers having various features from rubber-like polymers to vitreous polymers, and easy modification, there are many problems in strength and improvement in the compatibility between heat resistance and tenacity. Poor tenacity is a general problem common to the acrylic resins, and some methods for solving this problem has been reported. For example, rubber particles have been added in the resin (Japanese Patent Application Laid-Open (JP-A) Nos. 58-167605 and 3-52910). However, the problem of whitening arising by bending the resin (bend processibility) as well as incompatibility between transparency and heat resistance cannot be solved by these methods.
Applications of the acrylic resin as an optical element, particularly an optical elements using short wavelength lasers (around 400 nm), have been attempted by taking advantage of excellent transparency of the acrylic resin. However, the application field of the acrylic resin is restricted since it is deficient in tenacity and heat resistance despite its high transparency. While use of the acrylic resin to optical recording discs have been attempted in recent years, it has been a crucial problem to improve surface smoothness and scratch resistance upon processing into a film or sheet in addition to insufficient heat resistance and tenacity. There have been no acrylic resin that satisfies heat resistance, tenacity, scratch resistance of the surface and surface smoothness of films and sheets while maintaining acrylic resin's own transparency.
Accordingly, resins capable of readily forming blend polymers and exhibiting novel performance, particularly capable of being compatible between these contradictory characteristics, and resin compositions comprising these resins have been desired.